I am currently leading up the end of Act 1 of my campaign. In Act 2, I intend to have the players traveling the world to collect MacGuffins to stop a nasty ritual. However, I am having trouble deciding what exactly those things are. Any cool ideas?
That's not a lot to go on.
One good way to stop a ritual is to kill the ritualists. Of course, if they're part of a death cult, that might not be more than a speed bump...
But you want MacGuffins.
So ask yourself, WHO is doing the ritual? Do the ritualists belong to an organization? A religion? Are there obvious things int he world that are ANTI- to whatever that organization believes? For example, a death cult might run screaming from a phoenix.
Ask yourself, WHO is answering the ritual? Is it a ritual to summon a demon lord into the world? Something else? If it's not summoning something, is it a ritual that begs some patron deity to do some big awful thing? If the ritual requires someone or something out there to answer the ritual, then maybe that guy has some enemies who have MacGuffins that might counter him. If the ritual is bringing a demon lord to the world, maybe bringing some archons to the ritual will stop it, espcially if we have some MacGuffins that can summon/gate/bind archons.
If nobody is answering the ritual (maybe it just causes something bad to happen like a giant earthquake), then ask yourself, WHAT can stop or oppose the outcome of the ritual? Maybe there is an artifact of Calm Earth out there in the world somewhere that can stop any earthquake, and maybe bringing such an artifact to the ritual could even stop the ritual before there is an earthquake.